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Spaceship Landing

Your refrigerator or AC works because the power plant is outside your house and hence spills waste heat somewhere else. ...

My refrigerator works because it cools the food at the expense of the kitchen overall, which grows warmer. My kitchen in turn is cooled by my house AC, which cools a working fluid, transfers the heat outside my home, passes air over the cooled working fluid, pushes the air into the kitchen, then recovers the warmed air through some inlet near the AC, if I recall correctly. The local wind then blows the heat exhausted by my AC into the general environment, where etc. etc. Both my refrigerator and my AC are making matters worse on a universal scale, but they're making matters tolerable on a local scale. I am an unrepentant heat polluter. :D

The laser question amounts to whether 1) it is possible to take the heat from a heat source to generate a laser beam, and 2) whether transferring that heat from the place it's occurring to the place where you intend to generate the laser beam and then discharging that heat as a laser beam - along with the heat generated by generating the laser beam, is more efficient than discharging that heat by passing it through a heat exchanger and just letting the heat exchanger glow into space. One way or the other, the heat will be discharged as light of some wavelength in some manner unless you come into contact with some matter or discharge some heated matter into space. My gut tells me the laser is a colorful but impractical solution since you're going to need a way to discharge the waste heat from the laser itself as well as the waste heat from the whole process of delivering the heat from the place its occurring to the location of the laser; why bother with the laser when you're still needing a heat exchanger at the end of it all?
 
My refrigerator works because it cools the food at the expense of the kitchen overall, which grows warmer. My kitchen in turn is cooled by my house AC, which cools a working fluid, transfers the heat outside my home, passes air over the cooled working fluid, pushes the air into the kitchen, then recovers the warmed air through some inlet near the AC, if I recall correctly. The local wind then blows the heat exhausted by my AC into the general environment, where etc. etc. Both my refrigerator and my AC are making matters worse on a universal scale, but they're making matters tolerable on a local scale. I am an unrepentant heat polluter. :D

The laser question amounts to whether 1) it is possible to take the heat from a heat source to generate a laser beam, and 2) whether transferring that heat from the place it's occurring to the place where you intend to generate the laser beam and then discharging that heat as a laser beam - along with the heat generated by generating the laser beam, is more efficient than discharging that heat by passing it through a heat exchanger and just letting the heat exchanger glow into space. One way or the other, the heat will be discharged as light of some wavelength in some manner unless you come into contact with some matter or discharge some heated matter into space. My gut tells me the laser is a colorful but impractical solution since you're going to need a way to discharge the waste heat from the laser itself as well as the waste heat from the whole process of delivering the heat from the place its occurring to the location of the laser; why bother with the laser when you're still needing a heat exchanger at the end of it all?

well, one point to bear in mind that a ship in orbit, unlike a household AC, has no exterior fluid to pass heat into, and can only shed heat by black body radiation. Now, I realise the topic at hand has said ship on a fuel skimming mission, but still, its in a very low pressure or even near vacuum environment, which means it cant rely on convection or conduction of heat, as theirs nothing to conduct into, it can only radiate.
 
We have to consider the reference frame.

The ship isn't moving and gas travelling at 10km/s is entering the tanks...

OK, that is one possible frame of reference. It is probably convenient to look at the gas flow, but not very convenient for looking at the total energy state of the ship.

Your model seems to convert total air temperature directly into internal heat energy? That presumes a closed system, but since we collect gas the system is not closed. That might approximate a jet engine if we squint hard enough, since it releases roughly as much mass as is ingests, but at a guess it is not an appropriate model for fuel scoops.
 
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My refrigerator works because it cools the food at the expense of the kitchen overall, which grows warmer.
A ship does not have the luxury of using free power from "somewhere else", it has to include the power plant, and hence generate a lot more heat than the heat moved from the fridge.

In essence a ship is a fridge with the power plant inside, and no kitchen to conveniently dump heat into.



The laser question amounts to whether 1) it is possible to take the heat from a heat source to generate a laser beam, and 2) whether transferring that heat from the place it's occurring to the place where you inte...

This is exactly what the second law of thermodynamics talks about. Basically you ask if it is possible to build a perpetuum mobile by powering it with its own waste heat. The answer is no; trying to convert the waste heat to usable energy would be decreasing entropy, it can only be done by increasing entropy more somewhere else, i.e. generating even more waste heat.
 
OK, that is one possible frame of reference. It is probably convenient to look at the gas flow, but not very convenient for looking at the total energy state of the ship.
I agree, it is a simplification and there are many other factors to consider.

Your model seems to convert total air temperature directly into internal heat energy?
No, it is considering the entire mass of gas scooped as a 'thing', and considers the bulk energy transfer necessary to take a gas at a high energy state and remove said energy to elsewhere - it is an over simplification and I can go into much more detailed maths for it but for the sake of a 'plausible scientific estimate' it will suffice.
That presumes a closed system, but since we collect gas the system is not closed. That might approximate a jet engine if we squint hard enough, since it releases roughly as much mass as is ingests, but at a guess it is not an appropriate model for fuel scoops.
I am abstracting it to a 50,000kg 'block' of air so that I can consider it a closed system to simplify the physics of it to simple energy calculations rather than dip back into much more complicated math. There may be the odd order of magnitude difference here and there but its probably close enough to get an idea of the process.
 
Traveller has one other energy sink - Motion.

Manoeuvre drives turn energy into acceleration (in contradiction of physics). Can't the heat go there too?
 
As I understand the heat dilemma in spaceships, heat has to have something to latch onto, which would be where gas comes in.

And then goes, transformed into plasma and jettisoned out the backdoor.
 
You need a process to turn the waste heat into something else - which requires an energy input which generates more waste heat.

Take a packet of m&m s - scatter them across the table.

To do useful work the m&m s need to be eaten by a hamster.

The hamster can crawl to reach the m&m s - but needs to do work to do this.

Or you can tip the table so the m&m s flow towards the hamster - but this also requires work.
 
As I understand the heat dilemma in spaceships, heat has to have something to latch onto, which would be where gas comes in.

And then goes, transformed into plasma and jettisoned out the backdoor.
That just makes the gas you are heating the heat sink, and once you run out of gas you can not dump the waste heat.

How to you get the waste heat to the gas to turn it into a plasma? How to you control the flow of the plasma?
 
I'm lucky to have passed high school science, my aces were in the arts.

It really depends on the ratio of created heat to available disposable gas; and preheated gas could be fed to the fusion rockets, or whatever form the fusion reactor takes.

Or compacted into fusion gun pellets.

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How do you feed it into the fusion exhaust?
How do you compact it into the fusion gun pellets?

The answer to both of those questions is you need to do work which means you generate yet more waste heat.

Go and do a course on thermodynamics - there are many online courses, brilliant.com youtube videos and the like.

In out modern world if you misquote Shakespeaerae you are considered to be cave dwelling undermenschen, and yet 99.999% of 'educateted' arts graduates haven't got a clue about basic science - and yes, the laws of thermodynamics are basic science.
 
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In our modern world if you misquote Shakespeaerae you are considered to be a cave dwelling undermenchen, and yet 99.999% of 'educated' arts graduates haven't got a clue about basic science - and yes, the laws of thermodynamics are basic science.

Untermensch. "-en" is the pural suffix, equivalent to "-s" in English (Ie "you are considered to be a subhumans")

I agree with your basic point, though. the trouble is out society is lead by the media, and the media is composed of those who enjoyed media studies more than the sciences (naturally enough).
 
I am well aware of the meaning of the words I typed.

The 'scientifically illiterate' in the majority of cases are unaware of their scientific ignorance.

A lot of today's stupidity would end if a few medics and scientists would actually risk the pitchforks and torches of the cancel culture twatteraty and explain basic biology to the scientifically challenged.

I'm actually surprised no one has mentioned my spelling of Shakspeare yet... (I am pretty certain the majority on here will get the joke).

Anyway back to the original thread :)
 
and yes, the laws of thermodynamics are basic science.
While they are basic science, you're pushing close to group attack with the arts major bit. (noting that you've been aware in the past I'm one of those Arts majors...)

The problem is that they're not something intuitive to many. Why? Because a lot of work we do is still technically (in physics speak) using heat to do work. People aren't taught that engines in cars are about 25% (peak around 35%) efficient at converting heat to work. The remainder is waste heat... And that the work also turns to heat. Pretty much everything results in waste heat.
 
I though all the waste heat was routed in to the pet singularity stored in that small closet next to engineering with the big DO NOT OPEN sign on it.
 
Let's consider that nothing is possible without the discovery of how to viably manipulate gravity at technological level eight; this probably led to the creation of a viable and reliable fusion bottle, that permits the use of viable fusion reactors.

Do I think that gravitational manipulation is possible within our current (eight) technological level? Not in real life.

Having available a fusion bottle, we pump it full of preheated plasma, crank up gravitational pressure to eleven, and carefully convey that fusion pellet to a fusion gun, if in combat, or feed it to the fusion rocket.
 
Let's consider that nothing is possible without the discovery of how to viably manipulate gravity at technological level eight; this probably led to the creation of a viable and reliable fusion bottle, that permits the use of viable fusion reactors.
I agree, the Traveller tech paradigm is underpinned by gravitics for TL8.
Gravitics grant - null grav modules, the maneuver drive, artificial gravity, acceleration compensation, the jump drive, and grav catalysed fusion (not to mention grav focussing for lasers)

Do I think that gravitational manipulation is possible within our current (eight) technological level? Not in real life.
Without a genius level brekthrough or someone having an Emperor's new clothes moment probably not.
General relativity has passed every experiment we have thrown at it, yet there is the issue of universe expansion and galactic movement requiring a couple of fixes - notably dark energy and dark matter.
Then there is the singularity issue - we know black holes exist and yet the maths and physics for them requires a theory of quantum gravity to tie everything up.

Problem is none of the theories can pass even basic scientific tests. String theory is dogma, not even a testable hypothesis, loop quantum gravity at least gave a testable hypothesis that it experimentally failed.

Dark matter and dark energy are similarly untestable - they fix issues in observations so they must be right... there is always the possibility that there is another explanation or even the observations have a critical flaw.


Having available a fusion bottle, we pump it full of preheated plasma, crank up gravitational pressure to eleven, and carefully convey that fusion pellet to a fusion gun, if in combat, or feed it to the fusion rocket.
How do you pre-heat the plasma, how do you move the plasma to the gun or rocket?
At each step you are doing work and generating yet more waste heat.
Oh, and how efficient are your grav generators - because cranking up the gravitational pressure requires you do do work which generates...

Another Dilbert has already summed this up better that I have ever managed.

A starship is a fridge with the engine on the inside. The only ways to remove waste heat are to radiate it or to throw something that is hot out of the spaceship.
This is why I invented the gravitic heat sink :)
 
It has been suggested - Hans used to propose a sub-space heat sink. My issue with that is there is no mention of Star Trek like sub-space in the Traveller tech paradigm.

This is why I opted for gravitics based heat sinks since at least we already have gravitic handwavium and we need heat sinks at the same time as fusion reactors.
 
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